Elisabete Freitas

• PhD
• Professor at University of Minho

Ageing of asphalt pavements is an inevitable phenomenon that reduces the overall lifespan of the road network. Typically, this process is simulated in the lab, however several climatic factors are often overlooked in such simulations. To evaluate the ageing effects more realistically, a network of universities in six Western-European countries was...

In cold regions, icy roads cause hazards that extend beyond accidents, impacting communities and escalating air pollution during congestions. To reduce the risk of road accidents caused by ice formation on the pavement surface, new coatings have been developed to create superhydrophobic asphalt mixtures to avoid this issue. This study investigated...

The acoustic environment in urban spaces is often dominated by human-made noise sources, with road traffic noise as the most pervasive. Meanwhile, urban planning often overlooks how soundscape can impact citizens' well-being. This study combined virtual reality, biometric sensing, and questionnaires to evaluate how urban design measures targeting r...

Road markings (RM) consist of two distinct layers: the paint layer and the retroreflective layer. Together, they function as system and are essential features for road safety. Recent studies have been centred on elevating these systems to a smarter level, imbuing them with novel functionalities, increasing their visibility, service life and road sa...

Road markings (RMs) typically consist of a paint layer and a retroreflective layer. They play a crucial role in road safety by offering visibility and guidance to drivers. Over their lifetime, dirt particles, oils, and greases are adsorbed on the RM surface, reducing their visibility and service life. A self-cleaning ability has been widely studied...

BRISA is employing efforts to evaluate the pavement influence as a factor of source noise reduction, while studying forms of adjusting the applicability of the CNOSSOS noise prediction method to the reality of the concession road network, in order to comply with European directives about Environmental Noise evaluation and management. This Project e...

Virtual studies involving pedestrians have gained relevance due to the advantage of not exposing them to actual risk, and simulation setups have benefitted from rapid technical advancements, becoming increasingly complex and immersive. However, it remains unclear whether complex setups affecting participants’ freedom of movement impact their decisi...

This study investigates the effect of iron-modified nano-TiO2, using the co-precipitation method with different concentrations of FeCl3 (0.1, 1, and 10%), to improve its photocatalytic properties for outdoor applications. To this end, modified and unmodified nano-TiO2 were characterized using different techniques. The optical properties were charac...

The advent of autonomous vehicles (AVs) has sparked many concerns about pedestrian safety, prompting manufacturers and researchers to integrate external Human–Machine Interfaces (eHMIs) into AVs as communication tools between vehicles and pedestrians. The evolving dynamics of vehicle–pedestrian interactions make eHMIs a compelling strategy for enha...

Nowadays, the growing concern about improving thermal comfort in different structures (textiles, buildings, and pavements, among others) has stimulated research into phase change materials (PCMs). The direct incorporation of PCMs into composite materials can cause mechanical impacts. Therefore, this study focuses on the design of phase change coaxi...

Nowadays, the growing concern about improving thermal comfort in textiles, asphalt pavements and buildings has stimulated research into phase change materials (PCMs). However, the incorporation of PCMs directly causes mechanical impacts. Therefore, this study herein reported focuses on designing coaxial phase change fibres using commercial cellulos...

Environmental noise control regulations typically employ noise level descriptors to set limits for noise exposure. However, other characteristics of noise, such as frequency content, temporal patterns and masking, have been proven to influence the perception of acoustic environments. In this sense, psychoacoustic indicators offer an objective means...

Albedo plays a vital role in urban microclimates. Civil engineering structures usually absorb a high amount of energy in form of heat, for example asphalt pavements, which have a low albedo, thus contributing to the Urban Heat Island (UHI) effects. Modifying the physical characteristics of asphalt pavements, including reflectance and thermal proper...

Road traffic noise is the most common source of community noise in urban areas, causing adverse impacts on the health and well-being of the exposed population. Therefore, mastering road traffic noise perception is key to tackling noise pollution. Vehicle noise is mainly produced by the tyre/pavement interaction, especially for light vehicles, which...

This research presents a dual-pronged bibliometric and systematic review of the integration of phase change materials (PCM) in asphalt pavements to counteract the urban heat island (UHI) effect. The bibliometric approach discerns the evolution of PCM-inclusion asphalt research, highlighting a marked rise in the number of publications between 2019 a...

A smart asphalt mixture holds new capabilities different from the original ones or can react to a stimulus. These capabilities can be categorized based on smartness or function: smartness, mechanical, electrical, optical, energy harvesting, electromagnetic wave/radiation shielding/absorbing, and water related. The most important capabilities applie...

A significant percentage of pedestrians walk in social groups (friends, families, or acquaintances who walk together). Although patterns generated by social interactions among group members have been shown to affect crowd dynamics, studies on the effect of social interactions at different crossing phases under low pedestrian density are limited. Th...

A set of road traffic pass-by noises containing more than 2000 vehicles was recorded following the Statistical Pass-By (SPB) methodology (ISO 11819-1:2022). Besides the acoustic descriptors, psychoacoustic indicators (loudness, sharpness, roughness, fluctuation strength) were retrieved for each pass-by of the three vehicle categories defined in the...

Pavement surface characteristics have been gaining relevance with the changing mobility paradigm as they greatly contribute to the degree of safety, comfort, environmental quality and long lasting pavements. The surveillance methods of pavement surface characteristics have evolved from manual to semi- and automated methods and also to more cost-eff...

This research reports a simple, innovative, and low-cost doping method of TiO2 nanoparticles presenting the effects of calcination and the weight ratio of TiO2:FeCl3 (1:0.33–1:4.5). The photocatalytic activity of the nanomaterials was investigated by decolorizing Rhodamine B (RhB) dye in an aqueous solution. The main results showed that there is an...

Asphalt road pavements are usually dark and, consequently, have a low albedo. Therefore, they absorb energy as heat, increasing the Urban Heat Island (UHI) effect, which impacts the environment, energy consumption, and human health. Through the functionalization with thermochromic materials (TM), this work aims to develop a smart asphalt pavement a...

While sound absorption is an acoustic related property reasonably well known and currently used to characterize low noise surfaces, damping is a property commonly used in other domains to define the energy dissipation of a material but rarely used to characterize this important mechanism in road pavements. This paper compares noise related properti...

Thermochromic materials change their optical response to temperature reversibly. This study explores the application of thermochromism to road engineering, which is still incipient in this area, from two perspectives. The first one is about the development of functionalized road markings (FRM) working as thermochromic sensors to alert the presence...

To achieve high photocatalytic activity, TiO 2 nanoparticles nanoparticles require an excitation source in ultraviolet radiation. Incorporating chemical elements into the TiO 2 lattice can tune its band gap, resulting in an edge-shifted red absorption to reduce energies, improving photocatalytic performance in the visible region of the electromagne...

Phase change materials (PCMs) have been incorporated into asphalt concrete pavements because they can regulate the temperature by absorbing and releasing heat during physical state changes. This effect reduces temperature gradients of pavements and, consequently, increases its service life. This work presents a systematic review of recent articles...

RESUMO A finalidade geral dos pavimentos rodoviários consiste na capacidade de resistir ao tráfego rodoviário e as ações meteorológicas, garantindo condições de rolamento seguras e confortáveis, com o menor dispêndio possível de recursos e danos sobre o meio ambiente. Um pavimento rodoviário é considerado inteligente quando possui funcionalidades a...

The functionalization of asphalt mixtures is carried out in order to provide new capabilities to the road pavements, with major social, environmental and financial benefits. Optical characterization techniques as well as optical processes like photocatalysis play a major role in the development of new asphalt mixtures with smart functions. These ad...

Asphalt pavements are designed to resist weathering and road traffic while guaranteeing safe and comfortable driving conditions at low cost and with minimal environmental impact [...]

It is known that pollutants and their irreparable influence can considerably jeopardize the environment and human health. Such disastrous, growing, hazardous particles urged researchers to find effective ways and diminish their destructive impacts and preserve our planet. This study evaluates the potential of incorporating Titanium Dioxide (TiO2) s...

Sumário As misturas betuminosas funcionalizadas com capacidade fotocatalítica promovem a limpeza do ar, sendo consideradas técnicas que contribuem para o novo modelo socioeconómico conhecido como Green Recovery, por serem consideradas tecnologias limpas. Nesta investigação, a mistura betuminosa AC 10 foi funcionalizada a partir da técnica de pulver...

Sumário A coloração preta dos pavimentos rodoviários acentua a absorção de energia em forma de calor e contribui para o fenómeno de ilha de calor, que possui impactos relacionados com o ambiente, o consumo de energia e a saúde. Através da concessão de novas habilidades (funcionalização) por aspersão superficial de um revestimento contendo uma soluç...

Aging by oxidation of asphalt roadway material promotes changes in its physical, chemical, and rheological properties, affecting its hardening and accelerating the degradation of its corresponding asphalt mixture. Titanium dioxide (TiO2) has been applied in engineering investigations to promote anti-aging and photocatalytic properties. In this stud...

The determination of the band gap energy (Eg) of semiconductors powder materials can be performed from diffuse reflectance spectroscopy (DRS) measurements. For this purpose, the classical theory proposed by Kubelka and Munk (K-M) and the so-called plot Tauc, both discussed here, have been largely employed. We investigate the Eg values of anatase Ti...

Pavement Management Systems use models describing performance indicators and can be used to plan future maintenance and rehabilitation activities taking into account the safety and economic requirements. The COST Action 354 (Long Term Performance of Road Pavements), with the participation of experts from 15 European countries, has established a lis...

The sustainable development of our societies demands strong efforts on scientific and technological research while informing and educating students and the general population. Air pollution and road safety hazards constitute two main public health problems that are insufficiently addressed pedagogically. With this work, we aim to contribute to tack...

Combining Computer Vision (CV) and Anomaly Detection (AD), there is a convergence of methodologies using convolutional layers in AD architectures, which we consider an innovation in the field. The main goal of this work is to present different Artificial Neural Networks (ANN) architectures, applying them to distress detection in road pavements and...

Virtual reality is becoming an important tool for studying the interaction between pedestrians and road vehicles, by allowing the analysis of potentially hazard situations without placing subjects in real risk. However, most of the current simulators are unable to accurately recreate traffic sounds that are congruent with the visual scene. This has...

Road pavements are designed to withstand road traffic and weathering actions while ensuring comfortable and safe riding conditions as well as low costs and damage to the environment. When a road pavement has additional abilities or reacts to an external stimulus, it is considered to be smart and multifunctional. Examples of such abilities that have...

The controlled study of pedestrians’ crossing decision-making is relevant to the search for better safety conditions for this class of vulnerable road users. Several risk factors have been identified in the literature related to the crosswalks’ surrounding environment, the socio-demographic characteristics of the pedestrians crossing the road and t...

The determination of the optical band gap energy (Eg) is important for optimization of the generation of electron/hole pairs in semiconductor materials under illumination. For this purpose, the classical theory proposed by Kubelka and Munk (K-M) has been largely employed for the study of amorphous and polycrystalline materials. In this paper, the a...

This work evaluated the photocatalytic activity of 3D-printed cementitious mortar specimens functionalized with TiO2 nanoparticles to obtain a multifunctional and smart concrete. This research aims to assess the influence of different parameters related to the functionalization process such as adsorption, coating time gaps, and coating rates on the...

Recently, several studies on pedestrian safety and particularly those addressing pedestrian crossing behaviour and decision-making, have been performed using virtual reality systems. The use of simulators to assess pedestrian behaviour is conditioned by the feeling of presence and immersion, for which the sound is a determining factor. This paper p...

1 Abstract Virtual reality is becoming an important tool for studying the interaction between pedestrians and road vehicles, by allowing the analysis of potentially hazard situations without placing subjects in real risk. However, most of the current simulators are unable to accurately recreate traffic sounds that are congruent with the visual scen...

This paper identifies and analyzes variables that influence pedestrian safety based on the definition of models of pedestrian crash frequency for urban areas in Portugal. It considers three groups of explanatory variables, namely: (i) built environment; (ii) pedestrian infrastructure, and (iii) road infrastructure, as well as exposure variables com...

Surface dressings are a sustainable maintenance alternative for pavements with surface distresses, due to the low amount of resources involved. This paper aims to analyze the viability of using twelve different surface dressing solutions, including three binders (conventional and modified emulsions, and a soft 160/220 bitumen) and a covering with d...

The development of a linear mixed model to describe the degradation of friction on flexible road pavements to be included in pavement management systems is the aim of this study. It also aims at showing that, at the network level, factors such as temperature, rainfall, hypsometry, type of layer, and geometric alignment features may influence the de...

Transportation noise is considered today a major environmental risk factor and an important public health issue, especially in urban settings. Road, railway, and aircraft transports can produce high levels of continuous or intermittent noise, which, upon continued exposure, may have both short- and long-term impacts. Relevant short-term impacts are...

This research aims to develop asphalt mixtures with new capabilities, namely photocatalytic, superhydrophobic, and self-cleaning capabilities. Different solutions were prepared combining nano-TiO 2 and micro-PTFE on water, ethyl alcohol, and dimethyl ketone with different concentrations. The solutions were sprayed over the asphalt mixtures, and the...

Transparent binder is used to substitute conventional black asphalt binder and to provide light-colored pavements, whereas nano-TiO2 has the potential to promote photocatalytic and self-cleaning properties. Together, these materials provide multifunction effects and benefits when the pavement is submitted to high solar irradiation. This paper analy...

Transparent binder is used to substitute conventional black asphalt binder and to provide light-colored pavements, whereas nano-TiO2 has the potential to promote photocatalytic and self-cleaning properties. Together, these materials provide multifunction effects and benefits when the pavement is submitted to high solar irradiation. This paper analy...

When crossing a road, pedestrians must detect traffic, combine data coming from different perceptual modalities, evaluate the time envelope for safely cross the street, and monitor the position of oncoming vehicles to perform corrective actions if needed. This study analyzed the influence of noise emitted by vehicles, or its absence, on pedestrians...

A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), to generate a document that supports the development of future research, compiling the various studies focused on the analysis of the pedestrian-vehicle interaction at unsignalized crosswalks. Firstly, 381 studies were identi...

The most adverse weather condition for road safety happens when there is water, snow, or ice on the road surface because their presence highly decreases friction. Therefore, it is essential to drain or repel them quickly. If the water drops are repelled from the surface or the ice/snow formation is avoided with the application of superhydrophobic c...

Nowadays, there is increasing concern in transportation engineering about the use of techniques less harmful to the environment and also about road safety. Heterogeneous photocatalysis based on the application of semiconductor materials onto asphalt mixtures is a promising technology because it can mitigate air pollution and road accidents. The fun...

There is an increasing concern about the recycling and reuse of wastes in differ-ent areas. This research aims to analyze the technical viability of the use of Reclaimed Asphalt Pavement (RAP) and Steel Slags (SS) for the composition of asphalt mixtures for surface lay-ers. Therefore, three asphalt mixtures AC 10 were designed: without recycled mat...

The aim of this research is to develop multifunctions on recycled asphalt mixtures for the surface layer of road pavements. Therefore, preliminary research on functionalization has been carried out. Afterwards, the asphalt mixtures were designed and characterized by mechanical and superficial point of views. The next step is the design of the nanom...

Photocatalytic asphalt mixtures have the capability of mitigating air quality problems and degrade oils/greases by using semiconductors. The techniques to do so can change their functional characteristics. This study aimed to analyse the functionalization effect on the essential surface characteristics, such as macrotexture, skid resistance, and mi...

Nowadays, there is an increasing concern about the use of less harmful techniques to the environment, and about road safety in Transportation Engineering. Heterogeneous photocatalysis based on the application of semiconductors materials onto asphalt mixtures is a promising technology because it can mitigate air pollution and road accidents. The fun...

A oxidação/envelhecimento do material betuminoso dos pavimentos rodoviários promove mudanças das suas propriedades físicas e reológicas, afetando o seu endurecimento e acelerando as degradações das misturas asfálticas. O dióxido de titânio (TiO2) vem sendo aplicado em investigações da Engenharia para promover propriedades anti-envelhecimento e foto...

Analisar a relação entre os acidentes entre veículos e peões e as várias características da infraestrutura e da sua envolvente é um passo essencial na identificação de medidas capazes de promover a segurança rodoviária. Neste trabalho estuda-se a influência das variáveis associadas ao ambiente construído, à infraestrutura pedonal e à infraestrutura...

Road pavement develops distresses over time, which increase tyre/road noise. This work focuses on the impact of these distresses on environmental noise. To calculate the environmental noise, a method to transform Close ProXimity (CPX) measurement results into the required input for traffic noise models was defined and used. The tyre/road noise leve...

Photocatalytic and self-cleaning asphalt mixtures have the capacity of mitigating air quality problems and degrade oils/greases. Their functional characteristics can change due to the presence of semiconductors. Thus, after the application of semiconductors on asphalt mixtures, the assessment of skid resistance and microtexture becomes important si...

A cost-effective solution to provide asphalt pavements with the photocatalytic property was addressed for the first time, based on the combination of low percentages of two semiconductors , TiO 2 and ZnO. Two photocatalytic techniques-spray deposition and bitumen modification-were used. With the former, the chemical properties were evaluated by FTI...

This research aimed to assess the factors – application procedure (after compaction versus during mix), influence of temperature (room temperature - RT; 60; 100 and 140 °C), spraying rate (4, 8 and 16 mL/cm2) and incorporation percentage by volume of TiO2 (3 and 6%) – based on RhB degradation.

Traffic accidents are among the leading causes of death around the world. The causes of its occurrence largely correspond to the human factor. With this, many studies are carried out to examine the main determinants underlying human behavior in traffic and more specifically, risk behaviors. The use of questionnaires to relate personality traits and...

Functionalization of road pavement asphalt mixtures provides new capabilities that can mitigate problems like air pollution and road accidents. In this research, nano-TiO2 and micro-ZnO were deposited through an aqueous solution by spraying it over the surface of asphalt mixture samples in order to promote the photocatalytic, superhydrophobic and s...

The negative impact of noise on human health is well established and a high percentage of environmental noise is related with traffic sources. In this study, we compared annoyance judgments of real and virtual traffic sounds. Virtual sounds were generated through an auralization software with input from close proximity tyre/road noise measurements...

The alarmingly high recorded accident rate in recent years has received a considerable attention from the road authorities resulting in stronger prevention campaigns. Irrespective of the meritorious efforts of relevant institutions, the number of victims due to accidents increases yearly. From theoretical training of drivers, the conditions of the...